HONG KONG SAR - Media OutReach - 1 November 2023 - CK Life Sciences Int'l., (Holdings) Inc. is presenting preclinical data for its investigational dual-antigen cancer vaccines, co-targeting PRAME (preferentially expressed antigen in melanoma) and PD-L1 (programmed death-ligand 1), on November 4at the 2023 Society for Immunotherapy of Cancer (SITC) Annual Meeting in San Diego, California, USA. The investigational cancer vaccines evaluated in the preclinical study contain antigenic sequences of PRAME and PD-L1 intended to induce anti-cancer immune responses. PRAME is a cancer antigen highly expressed in many different types of cancers and has been associated with different oncogenic processes. PD-L1 represents one of the most important immune checkpoint antigens highly expressed on cancer cells to limit T-cell activation in the tumour microenvironment. "CK Life Sciences has a growing pipeline of cancer vaccines in various stages of development. The preclinical efficacy results of our dual-targeting PRAME/ PD-L1 cancer vaccines in liver cancer are promising and we hope to start clinical trials in the coming years," said Melvin Toh, Vice President & Chief Scientific Officer at CK Life Sciences. "Liver cancer is the second most common cause of cancer death in Asia and remains a major unmet medical need. We plan to investigate the PRAME/ PD-L1 dual-targeting cancer vaccines further in liver cancer and other cancer types known to over-express PRAME and PD-L1." DETAILS ON POSTER PRESENTATION:

• Abstract 1336: Cancer vaccine co-targeting PRAME and PD-L1 exerts significant tumour growth inhibition in syngeneic mouse hepatocellular carcinoma models
• Authors: Kin-Tak Chan, Chen-Yi Chiang, Chai Ho, Melvin Toh, Hsin-Wei Chen
• Session Date and Time: Saturday, November 4th from 9:00 a.m. - 8:30 p.m. Pacific Standard Time

In this preclinical study, we investigated whether dual-antigen cancer vaccines co-targeting PRAME and PD-L1 could suppress tumour growth in both prophylactic and therapeutic syngeneic mouse hepatocellular carcinoma (HCC) models. Two recombinant fusion protein vaccines comprised of PD-L1 and PRAME with or without GM-CSF were synthesised and formulated with a Toll-like receptor 9 agonist CpG oligodeoxynucleotide and aluminum hydroxide for vaccination. In the prophylactic tumour model study, the vaccines were administrated subcutaneously twice at a two-week interval before implantation of mouse HCC cells expressing PRAME, followed by weekly vaccination. In the therapeutic model study, the vaccines were administrated weekly into the animals after tumour cell implantation. Body weight and tumour volume were measured three times a week. All mice experienced a recoverable body weight loss without any abnormal behavior or reduction of activity after vaccination. In the prophylactic model (n=10 mice), both fusion protein vaccines significantly inhibited tumour growth, with 76.4% (P<0.01) and 59.5% (P<0.05) tumour growth inhibition (TGI) compared to control group, respectively. Importantly, there were some vaccinated mice without palpable tumour mass at the end of the study. These results were consistent with that found in the therapeutic model study (n = 10 mice), in which both vaccines significantly inhibited tumour growth, with 43.4% (P<0.01) and 40.7% (P<0.05) TGI, respectively, and prolonged animal survival compared to the control group (P<0.01). The results of this preclinical study clearly highlight the potential of simultaneously targeting PRAME and PD-L1 by fusion protein vaccination in cancer immunotherapy. DISCLAIMER This press release may contain forward-looking statements regarding the Group's research and development projects which may involve risks and uncertainties. Actual results may differ materially from expectations discussed in such forward-looking statements. All information in this press release is for general reference only and is not intended as investment advice or medical advice. CK Life Sciences Int'l., (Holdings) Inc. does not warrant or represent, express or implied, as to the accuracy, completeness or updated status of such information. No liability will be accepted for any loss or damage howsoever arising from or in reliance upon such information.REFERENCES [1] Gradecki S, Slingluff C, Gru A. J Cutan Pathol. PRAME expression in 155 cases of metastatic melanoma. Accessed at https://onlinelibrary.wiley.com/doi/10.1111/cup.13876. [2] Oyama K, Kanki K, Shimizu H, Kono Y, Azumi J, Toriguchi K, Hatano E, Shiota G. Gastrointest Tumors. Impact of preferentially expressed antigen of melanoma on the prognosis of hepatocellular carcinoma. Accessed at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5465675/. [3] Thongprasert S, Yang PC, Lee J, Soo R, Gruselle O, Myo A, Louahed J, Lehmann F, Brichard V, Coche T. Lung Cancer. The prevalence of expression of MAGE-A3 and PRAME tumor antigens in East and South East Asian non-small cell lung cancer patients. Accessed...